Detergent manufacturers incorporate carboxymethyl cellulose and derivatives thereof into their laundry detergent products to improve the soil suspension profile, as well as other benefits such as anti-abrasion. However, with recent trends in the industry towards solid laundry detergents having improved dissolution profiles, and towards the growing consumer trend for washing at colder wash water temperatures, there is a need to improve the dissolution performance of carboxymethyl cellulose and derivatives thereof.
The Inventors have found that whilst small particles of carboxymethyl cellulose exhibit good dissolution, their incorporation into a solid laundry detergent renders the composition very prone to gelling. This in turn, impedes the solubility of the entire laundry detergent composition. Without wishing to be bound by theory, the inventors believe that upon contact with water, the surface of these small carboxymethyl cellulose particles become very sticky. When these small particles are in close proximity with other particles, they are very prone to macromolecular gel formation. Once formed, these macromolecular gels have very poor dissolution profiles. In addition, this surface gelling phenomena also impedes the dissolution of the core of the small particle. However, if the carboxymethyl cellulose particle is too large, then the dissolution performance is very poor.
Furthermore, the inventors have found that pre-hydrating the carboxymethyl cellulose particles with a carefully controlled amount of water reduces the risk of unwanted surface gelling phenomena. The inventors have also found that surface gelling phenomena is impeded by removing, or carefully controlling to very low levels of, electrolytes such as sodium chloride and sodium glycolate.